1. Technical Field
This disclosure relates to an extreme ultraviolet light source apparatus.
2. Related Art
Photolithography processes have been continuously improving for semiconductor device fabrication. Extreme ultraviolet (EUV) light at a wavelength of approximately 13 nm is useful in the photolithography processes to form extremely small features (e.g., 32 nm or less features) in, for example, semiconductor wafers.
Three types of system for generating EUV light have been well known. The systems include an LPP (Laser Produced Plasma) type system in which plasma generated by irradiating a target material with a laser beam is used, a DPP (Discharge Produced Plasma) type system in which plasma generated by electric discharge is used, and an SR (Synchrotron Radiation) type system in which orbital radiation is used.